manimの作法 その56

概要

manimの作法、調べてみた。
AnimatedStreamLines、使ってみた。

サンプルコード

from manimlib.imports import *

def joukowsky_map(z):
    if z == 0:
        return 0
    return z + fdiv(1, z)

def derivative(func, dt = 1e-7):
    return lambda z: (func(z + dt) - func(z)) / dt

def cylinder_flow_vector_field(point, R = 1, U = 1):
    z = R3_to_complex(point)
    return complex_to_R3(derivative(joukowsky_map)(z).conjugate())

class test(Scene):
    def construct(self):
        self.add_vector_field()
        self.begin_flow()
        self.add_circle()
        self.wait(5)
    def add_vector_field(self):
        vector_field = VectorField(cylinder_flow_vector_field, )
        for vector in vector_field:
            if get_norm(vector.get_start()) < 1:
                vector_field.remove(vector)
        vector_field.set_fill(opacity = 0.75)
        self.modify_vector_field(vector_field)
        self.add_foreground_mobjects(vector_field)
    def begin_flow(self):
        stream_lines = StreamLines(cylinder_flow_vector_field, colors = [BLUE_E, BLUE_D, BLUE_C], start_points_generator_config = {
            #   "delta_x": 0.125,
            #   "delta_y": 0.125,
        }, virtual_time = 5, )
        self.add(stream_lines)
        for stream_line in stream_lines:
            if get_norm(stream_line.points[0]) < 1:
                stream_lines.remove(stream_line)
        self.modify_flow(stream_lines)
        stream_line_animation = AnimatedStreamLines(stream_lines)
        stream_line_animation.update(3)
        self.add(stream_line_animation)
    def add_circle(self):
        circle = Circle(radius = 1, stroke_color = YELLOW, fill_color = BLACK, fill_opacity = 1, )
        self.modify_flow(circle)
        self.add_foreground_mobjects(circle)
    def modify_flow(self, mobject):
        pass
    def modify_vector_field(self, vector_field):
        pass

生成した動画

以上。